There are multiple genes involved in the determinism of obesity like: Leptin receptor (LEPR)6, Fat mass and obesity-associated gene (FTO)7,8, Single-minded homolog (SIM1) and Propiomelanocortin (POMC)9, Src homology 2B (SH2B) Adaptor Protein 1 gene, Peroxisome proliferator-activated receptor gamma gene (PPAR-γ)10,11, IL-6 572 (C > G, 190 C > T, and 174 G > C gene polymorphisms)12,13, angiotensin converting enzyme (ACE I/D), but also Tumor necrosis factor (TNF) alfa 308 G > A14. This evidence concerns the gene LEPR and obesity due to melanocortin 4 receptor deficiency.